Method of preparing compounded lubricating oil



Jan. 24, 1939.

J. T. RUTHERFORD ET AL METHOD OF PREPARING COM OUNDED' LUBRICATING OIL CAUSTIC SODA SOLUTION.

Filed Sept. 14, 1936 3 Sheets-Sheet l NAPHTHENIC ACIDS SULFURIC ACID.

NEUTRALIZED AND EXTRACTED FROM OIL.

CRUDE SODIUM NAPHTHENATE SOLUTION.

ACIDIFATION TO FRE NAPHTHENIC ACIDS.

HYDROCARBON SOLVENT.

AQUEOUS SODIUM SULFATE LIQUOR REMOVED.

WASTE AQUEOUS SODIUM SULFATE LIQUOR SOLUTION OF FREE SULFURIC ACID (87.5

SALT WATER NAPHTHENIC ACIDS IN SOLVENT ACID TREATMENT .(2 LBS. ACID PER GAL.

CAUSTIC SODA SOLUTION OF NAPHTHENIC ACIDS.)

SLUDGE FROM ACID TREATMENT SLUDGE REMOVED.

PURIFIED NAPHTHENIC ACIDS WASHED UNTIL NEUTRAL TO METHYL ORANGE.

' WASH WATER NAPHTHENIC ACIDS NEUTRALIZED AND HYDROCARBON HYDROCARBON SOLVENT SEPARATED.

' PURIFIED AQUEOUS SODIUM NAPHTHENATE SOLVENT lnven ions STOCK SOLUTION.

FIG. I

HE I A. FRANC/S I JOHN 7. RUTHERFORD Jan. 24, 1939.

J. T. RUTHERFORD ET AL METHOD OF PREPARING COMPOUNDED LUBRICATING OIL Filed Sept. 14, 1936 3 Sheets-Sheet 2 AQUEOUS SOLUTION PURIFIED SODIUM OF ALUMINUM NAPHTHENATE STOCK SALT suc As SOLUTION (HOT).

-a 0a- I PRECIPITATION OF AQUEOUS SOLUTION BASIC ALUMINUM OF cAusTIc SODA. NAPHTHENATE IN ALKALINE ENvIRoNMENT. LUBRICATING I 1 sTEAM NAPHTHENATE -0IL CURD THOROUGHLY THEN I HOT WATER. WASH WITH HoT WATER.

I HEAT UN(T|L SOLUTION) Is CLEAR DEHYDRATION gf THEN DILUTED WITH OR To A NAPHTHENATE coNcENTRATIoN OF I0%.

I SEMI-SOLID coNcENTRATE OF BASIC ALUMINUM NAPHTHENATE IN LUBRICATING 0IL. I coNcENTRATE AND LUBRICATING 0IL AfC MIXED T0 GIVE CONCENTRATION OF BASIC ALuMINuM NAPHTHENATE. I VISCOSITY OF COMPOUNDED sTI-: AM A T OIL REDUCED WITH SUPER 550-600 F. I HEATED 0PEN sTEAM. (0IL TEMP. 2I2-250'F).

' I sTEARIc ACID STEARIC ACID. :DISSOLVED IN OIL BLOOM AND/ OR COMPOUND TO COLOR OTHER COLORING SPECIFICATIONS AGENTS. WHEN NECESSARY.

DRAWN OFF.

In ven Z01 5 JOHN TRUTHERFORD HENRY ,4. FRANC/S Jan. 24, 1939. J. T. RUTHERFORD ET AL 2,144,855

METHOD OF PREPARING COM OUNDED LUBRICATING OIL Filed Sept. 14, 1936 3 Sheets-Sheet 3 Inventors JOHN 7. RUTHERFORD HE V A. FRANC/S Patented Jan. 24,

UNITED STATES LUBRIOATIN G OIL METHOD PREPARING John '1. Rutherford and Henry A. Berkele'y, Calii., asllgnors to Standard Oil Company of California, San Francisco, Calif., a corporation! Delaware 1 0 Application September 14, 1936, Serial No. 100.70; M 1

This invention relates to methods of preparing compounded mineral oils and more particularly to a method of preparing liquid lubricating oils which have the property of inhibitin or pre- 5 venting piston ring sticking in internal combustion engines.

As disclosed in the application of George L. -Neely, Serial No. 38,791 flied August 31, 1935, addition of certain metal naphthenates in small quantities to lubricating oils-inhibits piston ring sticking in internal combustion engines. The metal naphthenates therein disclosed, prepared by conventional methods, give this highly desirable property to the oil.

It has been found, however, that the particular method of compounding the lubricant ailects profoundly the properties of 'the completed oiland its eiilciency for lubrication purposes. 1 This is especially true when the metal naphthenate used I in the compounded oil is a basic metal naphthenate.

Accordingly, an object of the invention is to provide a process of compounding mineral oils containing an aluminum naphthenate to obtain a liquid lubricant oi tree-flowing, non-stringing consistency which has a viscosity within the range normally utilized in internal combustion engine crankcase lubricants.

r The invention has as an additional object'the '30 production of a compounded mineral all contaming a dissolved basic metal naphthenate in quantity suflicient to impart increased viscosity and stringiness to the oil but having viscosity reduced to a consistency such that the compounded oil will flow readily through the lubrication system of an internal combustion engine.

Another object 01' the invention is to provide a method of compounding lubricating oils containing basic metal'naphthenates to obtain a lubricant which gives lower' rates of wear on bearings and other engine parts, than do such compounded lubricants prepared. by previously described or known processes.

A further object oi. the invention is to provide 45 a method of compounding crankcase lubricating oils to obtain a-lubricant which has properties that insure against scoring, scratching or uneven wear of closely fitting parts such as piston rings and cylinder walls during the process of brealdng 50 in a new engine.

A further object of the invention is-to provide a method of reducing the increased viscosity produced in the oil by the presence of a metal naphthenate and to obtain a lubricant having a vis- 5 cosity approximately that of the original matic form the preparation and purification of sodium naphthenate stock solutions suitable for use in the process of compounding the lubricant.

Figure 2 is a diagrammati flow sheet illus- 1 trating .a method of prep lng compounded lubricating oils having superior lubricating properties and containing basic aluminum naphthenates f Figure 3 illustrates, in part schematlcally,1"a 20 form of apparatus which may be used for reducing the excessive viscosity of the compounded oil and for other compounding steps.

. Examination of the flow sheets indicates that the process embodies two major steps comprising, 25 first, the preparation of naphthenic acids and purified sodium naphthenate stock solution which is disclosed merely by way of example, and secend, the compounding of lubricating oils containing basic aluminum naphthenates. V M

The flow sheet .01 Figure 1 is believed be: self-explanatory. Study of this diagram shows that a selected petroleum 011 containing naphthenic acids is treated with an alkali such as caustic soda to neutralize and extract the naphthenic acids. The extracted acids are then freed from the aqueous solution by addition of sulfuric acid. The iree naphthenic acids are next dissolved with a solvent and treated with sulfuric acid to remove undesirable constituents such as tars and color bodies and finally neutralized with an alkali to give a purified aqueous stock solution of water soluble alkali naphthenates.

' Similarly, the compounding process disclosed schematically in Figure 2 may be brieflydescribed by pointing out that the purified aqueous sodium naphthenate solution is heated and basic aluminum naphthenate is simultaneously formed and dissolved in oil by adding suflicient caustic alkali to maintain the solution slightly alkaline while concurrently adding an aluminum salt and lubricating oil. The 'basic aluminum naphthenate-oil curd formed by this process is then steamed, washed with hot water, dehydrated, di-

-. luted with more lubricating on, reduced in viso mi cosity by treatment with steam, compounded with stearic acid, brightened, filtered, colored, and finally cooled.

The following specific example will serve to illustrate the preferred mode of practicing the process of this invention.

Preparation of naphthem'c acids and sodium naphthenate stock solution In order to avoid emulsion difficulties when extracting the naphthenic acids from petroleum distillates by the following specific method, it has been found that the oil treated should have a boiling range or approximately 500-700 F. Likewise, in order to avoid difficulty with emulsification during the purification of the extracted acids by the method herein specifically described, it has been found that the crude naphthenic acids contained in the distillate and extracted therefrom should have an acid number no lower than approximately 160. Also, crude acids having an acid number greater than approximately 190 (which yield purified acids having an acid number greater than 225-230) are generally undesirable as they have been found to give naphthenates which are more corrosive to parts being lubricated. (Acid number is the weight in milligrams of potassium hydroxide required to neutralize 1 gram of acids.)

The selected distillate is heated to a temperature of from to F., for example, and

suflicient 4 Baum caustic soda added to neutralize the acids in the stock. The mixture is blown slowly with air for one-half hour and allowed to settle for two hours. The aqueous sodium naphthenate solution which has then formed and settled out is separated and drawn off into a storage container.

The above crude sodium naphthenate stock solution is next purified asfollows:

The sodium naphthenate solution is placed in a suitable container, acidified with sulfuric acid while agitating with air. The naphthenic acids are freed by this treatment from chemical combination with the sodium and the free acids separate as an oily layer on the surface of the conversion water. This conversion water is an aqueous sodium sulfate liquor and is drawn off to be discarded. The naphthenic acid layer is retained in the container and five volumes of a light hydrocarbon solvent are added to each volume of the separated acids. This solution of naphthenic acids is then treated with 87.5% sulfuric acid at the rate of 2 lbs. of acid per gallon of crude naphthenic acids, the sulfuric acid being added in four separate equal dumps. Following each step in the acid treatment the sludge formed is withdrawn. After the acid treatment, the naphthenic acid solution is washed with salt water until free from mineral acidity as indicated by methyl orange, and until freefrom sulfates.

The naphthenic acids, still in solution, are next neutralized and extracted from the hydrocarbon solvent by treatment with 4 Baum caustic soda solution. The amount of caustic required to neutralize the naphthenic acids is determined in each case by hand sample. The hydrocarbon solvent separates during the neutralization process. The aqueous layer comprises a solution of purified sodium naphthenate and is withdrawn from the container. Sufiicient caustic or purified naphthenic acids are added, when necessary, to make the sodium naphthenate solution neutral.

The naphthenic acids in this puri ed 50di= arsaeoc um naphthenate solution have a higher acid number than that of the acids as originally ex tracted. For example, where the acid number of one batch of acids'orlginally extracted as crude sodium naphthenate was 181 that of the purified stock obtained from this crude solution was 215.

Typical batch quantities illustrating the above purification process are as follows:

It should be understood that the process of preparing and purifying the sodium naphthenate stock solution may be carried out either continuously or as a batch operation. The batch method has been described for the sake of simplicity.

Although the above described process constitutes one method of preparing and purifying naphthenate solutions, this invention is not limited to such a method. Various alternative processes may be adopted depending upon the nature of the oil being treated, the molecular weight of the naphthenic acids being extracted and other such factors.

Compounding lubricating oil containing basic aluminum naphthenate Preparation of the basic aluminum naphthenate according to thepreiorred procedure of this invention involves simultaneous precipitation and ,dissolution of the naphthenate in-a. lubricating oil.

The ingredients necessary'for a. typical batch are:

Purified sodium naphthenate solution-gals 500 50 B. caustic soda solution ..lbs 120 Aluminum sulfate solution (164 gals. water,

448 lbs. of aluminum sulfate (iron free) -..ga.ls- 190 Lubricating oil gals 900 The above quantities yield 1000 gals. of oil containing 10% aluminum dinaphthenate.

Purified sodium naphthenate solution is charged to a tank provided with a compressed air supply or other means for agitation. When necessary, the pH of this solution should be adjusted ,so that it is neutral or only slightly on the alkaline side, by addition of caustic soda or suitable acid such as sulfuric acid, depending upon whether the original stock is aci'd, neutral, .or too strongly basic. This solution is then heated to approximately F., for example, by means of open steam. The batch is now ready for the conversion to aluminum naphthenate and is thoroughly agitated with air or by other suitable means during the entire conversion process which process involves addition of caustic soda. aluminum sulfate and lubricating oil to the aqueous sodium naphthenate.

To convert the sodium naphthenate to a. basic aluminum naphthenate, caustic alkali and aluminum sulfate or other water soluble aluminum salt are preferably incorporated in the sodium naphthenate solution in the relative proportion of 1 equivalent weight of hydroxide per 3 equivalent weights of aluminum. Such a rate of addition will maintain the sodium naphthenate solution alkaline throughout the precipitation process and yield a naphthenate which analyzes as A1(OH)R2 (where R. represents a naphthenate radical). Aluminum mono-naphthenate, that is, Al(OH)2R, also comprises a satisfactory compounding ingredient. When the latter compound is to be prepared the proportions of caustic alkali and aluminum sulfate should be such that 2 equivalent weights of hydroxide are added per 3 equivalent weights of aluminum. Mixtures of these basic naphthenate compounds also may be used whether prepared separately or simultaneously, as for example by incorporating 1 /2 equivalent weights of hydroxide per 3 equivalents of aluminum.

The lubricating oil is added at a rate sufiicient to insure formation of a soft curd from which sulfates are easily washed out and which readily dissolves in lubricating oils, subsequently to be added.

The conversion process may either be a batch or continuous operation and incorporation of the above three ingredients (caustic alkali, aluminum sulfate and oil) in the sodium naphthenate solution may be efiected either continuously and simultaneously or concurrently in a stepwise manner. For example addition of 1490 cc. of 50 caustic soda, 7.9 gallons of aluminum sulfate solution (equivalent to 18.6 lbs. of aluminum sulfate) and 5 gallons of lubricating oil in a stepwise manner and in the order named while continuously agitating with air, comprises a satisfactory method of incorportion. This cycle of additions is repeated approximately 24 times for the above described batch and until the endpoint is reached as shown by the sudden loss of tendency to foam and by no further precipitation of aluminum naphthenate.

After precipitation of the basic aluminum naphthenate by the above mentioned method, the naphthenate is next blown with live steam for approximately 30 minutes, the conversion water removed, and the naphthenate-oil curd finally thoroughly washed several times with hot water. The wash water is drawn off after each washing operation. Approximately 100 gallons lubricating oil is then added to the naphthenate-oil curd, which is next dehydrated by heating to 300 F. to free it of contained water. Approximately 700 gallons of lubricating oil are finally added to the concentrated naphthenate oil solution to give a finished basic aluminum naphthenate concentrate containing 90% lubricating oil and 10% naphthenate. This mixture is heated and agitated until a clear, bright solution free from lumps is obtained.

The above aluminum dinaphthenate concentrate is a product of a semi-solid rubbery consistency convenient for storage or shipping purposes but requires further dilution with oil and particular compounding treatments to render it useful as a crankcase lubricating oil.

Figure 3 illustrates a form of apparatus used in compounding the finished oil and in reducing its excessive viscosity. This apparatus comprises a closed container I, provided at the top with an inlet charging line 2 controlled by a valve 3. Conduit 4, controlled by valve 5, provides an outlet for draining the container I. A manhole 6 in the top of the container also permits solids and other materials to be introduced into the container.

Conduit 1 controlled by valve 8 supplies steam to a closed heating coil drained by conduit 9.

A superheated steam inlet l controlled by valve l l is connected to a distributor M for treating the contents of the container with open steam. A compressed air inlet pipe I! controlled by valve I3 is also connected to the distributor l4 and constitutes a means for agitating the container contents in addition to the steam.

A suitable means for exhausting the gases, such as steam, in the container I comprises an ejector l1 operated by air supplied from conduit 15 controlled by valve IS.

The procedure followed in the concluding steps of the process which utilize the above described apparatus is illustrated by the following specific example.

The container I is charged through conduit 2 with 8,500 gallons of mineral crankcase lubricating oil, previously refined and blended to meet the usual specifications. This oil is heated to a temperature above 212, for example to 225 F., by means of the closed coil supplied with steam through pipe I. As the oil is being heated some Water may accumulate in the bottom of the container. This water should be drawn off and discarded when the oil reaches 210 F. or a temperature slightly thereunder. In order to avoid possible boiling over resulting from vaporization of entrained water, the batch should be carefully watched while passing through the temperature range 210-220 F.

Open steam is admitted through distributor I4 from supply line 10. The quality of the steam should be such that condensation of moisture in the oil is prevented. superheated steam at 555-600 F. and having'200-300 of 'superheat has been found satisfactory. The quantity of steam is increased until the oil is agitated violently thereby (a 2 inch valve nearly wide open).

The aluminum dinaphthenate concentrate, previously prepared, is now dumped into the oil through the manhole 6 in quantities sufficient to give a final concentration of approximately 1% basic aluminum naphthenate in the oil. Since the concentrate contains approximately 10% aluminum dinaphthenate the proportion added will be about 1 part concentrate to- 9 parts oil.

The above mixture is treated with the open superheated steam until the viscosity is broken. By the term breaking the viscosity is meant destroying the stringy consistency imparted to the oil by the aluminum dinaphthenate even when the naphthenate is present in amounts of as little as 1%. The temperature of the body of the oil during this steam treatment should be maintained above 212 F. and preferably below 250 F.

A simple operating test for string iness is made by placing oil on the fingers and separating them to measure the tendency'to string out. A convenient laboratory test comprises measurement of viscosity. When the viscosity drops to within 2% seconds Saybolt of that of the original oil,

, the viscosity is considered to be completely broken. An increase in viscosity in the order of seconds Saybolt is regarded as not substantial and therefore permissible in the completed oil.

The aluminum dinaphthenate content of the completed oil should be preferably approximately 1% by weight although more or less naphthenate (for example, A to 2%) may be used as circumstances demand. The aluminum dinaphthenate content is determined by diluting the compounded oil with neutral ethyl ether and titration of the diluted oil with a standardized alcoholic caustic alkali solution.

Stearic acid is added to the oil after or during the viscosity breaking operation. The oil is agitated until the acid is dissolved. Addition of free fatty acids such as stearic acid in amounts as small as 4% has been found to give the oil the property of preventing scoring or scratching of pistons, piston rings and cylinders under highly adverse conditions such as encountered when breaking in a new engine under heavy loads and/or high speeds.

After the stearic acid has completely dissolved, and the viscosity of the oil is broken, the compounded lubricant is cooled to a temperature of approximately 2l0-220 F. and blown with air to brighten. While at this temperature the oil is also filtered to improve clarity and general appearance. During the filtering operation it has been found desirable to use a filter aid such as fibrous diatomaceous earth.

As a final step in the manufacture of the oil, bloom and/or other coloring agents may be added to meet desired color specifications. The completed oil is then cooled to a temperature of 80 F. or lower.

An alternative method which has been used in preparing dilute solutions of naphthenates, in oil (for example, 1% magnesium naphthenate or 1% aluminum dinaphthenate in oil) involves precipitation of the naphthenate directly in the oil vby contacting an emulsion of the water-in-oil type comprising aqueous sodium naphthenate dispersed in mineral oil, with an aqueous solution of the precipitating metal salt. This method is entirely satisfactory for the preparation of normal naphthenates and operative to produce basic naphthenates. However, preparation of basic aluminum naphthenates by this method has been found to yield a product which contains somewhat more free naphthenic acids than obtained by the previously discussed method.

The following specific example illustrates the above alternative emulsion method.

Emulsify 10.5 gallons of purified sodium naphthenate stock solution and 1.25 pounds of NaOH as a 50 B. solution in 40 gallons of S. A. E. 40 lubricating oil. To this emulsion add slowly with continued agitation at 180-200 F., 8.0 gallons of aqueous A12(SO4)3 solution (9.4 pounds of A12(SO4)3 per gallon). Agitation and heating are continued until the precipitated basic aluminum naphthenate is dissolved in the oil. The oil which contains 5% basic aluminum naphthenate, is diluted with 4 volumes of lubricating oil and the aqueous sodium sulfate liquor separated. The 1% solution of naphthenate in oil is next washed with fresh water using open steam agitation while maintaining the oil at approximately 205 F., to remove sulfates.

Upon removal of sulfates by the above washing operation the completed oil has substantially the same viscosity and consistency as the original uncompounded oil. Consequently, the necessity of a viscosity breaking operation is avoided.

The oil so prepared is compounded with stearic acid brightened, filtered and colored as previously described relative to the first method of preparation.

As repeatedly mentioned throughout this specification, the particular method of compounding the basic aluminum naphthenate lubricant is of critical importance in that it affects profoundly, the lubricating efiiciency of the compounded oil.

For example, precipitation of the basic aluminum naphthenate from sodium naphthenate solutions by adding a solution of caustic soda and an aluminum salt solution separately and in proper relative proportions, might appear to be unimportant on superficial examination. As a matter of fact this feature is highly important. The caustic soda should be added at a rate sufiicient to maintain the naphthenate solution alkaline yet in quantities insuflicient to precipitate substantial quantities of the added aluminum salt as aluminum hydroxide. When this procedure is followed a naphthenate of uniform composition is obtained.

On the contrary if the aluminum salt and caustic solution be mixed together prior to incorporation in the sodium naphthenate solution the soluble aluminum salt is converted to the hydroxide and proper combination with the naphthenic acid ions of the sodium naphthenate solution is obtained only with considerable difiiculty, if at all. Similarly if all of the caustic soda is added to the sodium naphthenate solution prior to incorporation of the soluble aluminum salt, the first precipitate formed will comprise principally aluminum hydroxide; aluminum mono-naphthenate will next be formed and as the mixture becomes less and less alkaline the naphthenate formed will comprise first the dinaphthenate and finally the normal aluminum naphthenate will predominate. Such a composite mixture is less desirable for lubrication purposes than the uniform naphthenate obtained by the process of this invention because the mixture appears to be less stable as indicated by a higher corrosion rate on certain bearing metals.

Again, if all of the soluble aluminum salt is first added to the sodium naphthenate, subsequent addition of caustic soda tends to form aluminum hydroxide as a precipitate in the oil and this precipitate recombines with naphthem'c acids only with considerable difiiculty. This latter proposed method also results in removal of a portion of the naphthenic acids from the oil as sodium naphthenate with the resulting problems of waste or of recovery of these extracted ingredients.

The mineral oil is preferably but not necessarily added .during the precipitation process simultaneously with the aluminum sulfate and caustic soda to produce a naphthenate curd containing oil which is more easily washed free from sulfates and can be readily incorporated in oil and dehydrated. If the oil is not added during precipitation the basic naphthenate curd has a high melting point and is diiiicult to wash, completely dehydrate and incorporate in oil. If the oil is added to the aqueous sodium naphthenate prior to precipitation, the first portion of naphthenate precipitated takes up the oil so that the soap formed toward the end of the precipitation is comparatively free from oil and the same difiiculties exist in dehydration and dispersing uniformly in an oil solvent.

Mineral oils compounded with 1% basic aluminum naphthenate in the manner in which mineral castor oil stocks have been prepared, will have viscosities in the order of 500 to 600 (Furol) at 100 F., whereas the mineral oil before compounding will have a viscosity of about one-tenth thisfigure. Two methods of reducing the viscosity of the compounded oil to essentially that of the original oil can be used.

One method consists of heating the oil to a temperature in excess of 300 F., agitating to 9,144,855 dissolve the naphthenate, and maintaining this temperature for a period of from one to tour hours until there is no further reduction in viscosity which is, at this point, essentially the same as the original oil. The time required to complete this operation is dependent upon the temperature and upon the volume of oil being treated, etc. At higher temperatures the time is reduced materially and at temperatures of 250 F. or below the rate of viscosity reduction is so slow that it is not commercially practical.

The other method or reducing viscosity, which is the preferred method described in this specification, comprises steaming the oil with open steam while maintaining the oil at a temperature of from 2l2-250 F. To prevent condensation of moisture, temperatures above 212 F. are

desirable, but not absolutely necessary. This procedure for reducing viscosity avoids oxidation naphthenic acids which comprises mixing an aqueous solution containing a water-soluble polyvalent metal salt and an aqueous solution containing an alkali naphthenate while maintaining the alkalinity of said'mixture above pH 'lbut below the point at which substantial quantities of the hydroxide of said poly-valent metal are precipitated by concurrent addition of an alkali,

whereby a basic metal naphthenate is precipi-- tated. 1

5. A process as in claim 4 in which'said polyvalent metal is aluminum.

6. A process as in claim 4 in which the pH is efiects resulting from prolonged heating at high temperatures. The upper temperature limit is not critical, but should of course be below the boiling point of the oil. Temperatures above 250 F. are not necessary and oils have been sat- 230" F. for a: period of one-hall to one hour.

The nature of the chemical mechanism of the action of the steam during this viscosity breaking operation has not been established. Mere observation of physical eflects, however, definitely establishes that open steam indirect contact -isfactorily reduced in viscosity by steaming at with the compounded oil greatly accelerates the viscosity breaking operation. This phenomenon is regarded as unpredictable, andperhaps may be properly designated a catalytic one. In addition to its accelerating effect on 'the viscosity breaking operation, the steam serves to agitate the lubricating oil and to provide aprotecting atmosphere above the body of lubricant which prevents oxidation oi-the oil.

It should be apparent from the previous descripti'on that the process of this invention, in its broader aspects, is applicable to preparation of basic naphthenate compounds of poly-valent metals other than aluminum, for example, to

preparation of basic iron or chromium naphthenates. Likewise, soluble metal salts other than sulfates or mixtures of salts of diilferent metals can be used during the precipitation process. Various equivalent alkali can also be substituted for the caustic soda for controlling alkalinity of the sodium naphthenate solution during the precipitation process. Also, the viscosity breaking feature of the invention in its broader aspects is not limited to naphthenates but in-' cludes oil solutions oi organic carboxylic acidsin Accordingly, it is desired to include within the scope of this invention the various equivalents embraced within the spirit of the invention and the terms of the appended claims.

We claim:

1. A rocess ofbreaking the viscosity. of an oil con suilicient metal naphthenate in solution to substantially increase viscosity and stringiness, which comprises heating said oil at a temperature above 212 F., but below the boiling point or the oil and accelerating the viscosity breaklng operation by intimately contacting said. oil with open steam. j

2. The process of claim thenate is an aluminum naphthenate.

3. The process of claim l'in which the naphthenate is a basic aluminum naphthenate.

4; a process of preparing ab ut metal salt or 1 in which the neph consistency oi'the original oil.

metal naphthenate in oil which comprises c9m-,

mingling an aqueous solution containing a polyvalent metal capable of forming oil-soluble basic naphthenates with an aqueous solution of a water-soluble naphthenate while in intimate contact with suiiicient oilto dissolve the precipitated naphthenate, and maintaining the alkalinity of said mixture above pH 7, but below the point .at which the hydroxide of said poly-valent metal is formed in substantial quantities by concurrent additionof an alkali, whereby the basic naphthenate of said poly-valent metal is precipitated.

9. A process of preparing a solution of a basic metal naphthenate in a lubricating mineral oil traction without substantially increasing the viscosity of the oil, which comprises commingling an aqueous solution containing a polyvalent metal ion, an aqueous solution of a water soluble naphthenate, and said mineral oil fraction, and maintaining the alkalinity of said mixture duringsaid commingling operation above pH 7 but below the a point at which the hydroxide of said polyvalent metal is formed in substantial quan ties by concurrent addition ofan alkali hydro de whereby a basic naphthenate of uniform composition and minimum free acid content is 'formed and dissolved insaid oil in suflicient quantity to materlally increase the viscosity thereo,.and breaking the increased viscosity of said oil solution to the 10. A process of preparing a solution of a basic metal naphthenate in a lubricating mineral oil traction without substantially. increasing the viscosity of the oil, which comprises forming said basic naphthenate and simultaneously dissolving the same in said mineral oil in proportions suflicient to materially increase the viscosity of the oil, heating said oil solution to a temperature above 212 -F. but below the boiling point of the oil and accelerating the viscosity breaking operation by intimately contacting said oil with open steam 11. A process of preparing a solution of a basic metal naphthenate in a lubricating oil, said solution'being characterized by increased stability and low free acid content as measured by reduced corrosivity to' bearing metals, which comprises withan aqueous solution 01' a water- 1 soluble naphthenate a solution containing a polyvalent metal ion capable of forming oil-soluble basic naphthenates, maintaining the alkalinity of said mixture above pH '7 but below the point at which the hydroxide of said polyvalent metal is formed in substantial quantities by concurrent addition of an alkali hydroxide, dissolving the polyvalent metal naphthenate in a lubricating oil in quantities sumcient to increase the viscosity and stringiness of said oil, and breaking said viscosity by heating at a temperature above 212 F. but below the boiling point of the oil and until the consistency of said oil is reduced to that at which it will readily flow through the lubrication system of internal combustion engines.

12. The process of claim 11 in which the precipitation is carried out in the presence of a lubricating oil to dissolve the precipitate as formed.

13; A process of preparing a liquid lubricating oil capable oi inhibiting piston ring sticking in internal combustion engines which comprises commingling a solution containing a polyvalent metal ion capable of forming oil-soluble basic naphthenates with an aqueous solution of a watersoluble naphthenate, maintaining the alkalinity of said mixture above pH '7 but below the point at which the hydroxide of said polyvalent metal is formed in substantial quantities by concurrent addition of an alkali hydroxide, concurrently adding lubricating oil whereby the basic naphthenate 01 said polyvalent metal is precipitated in the presence of the lubricating oil, dissolving said basic naphthenate in the oil in quantities sumcient to increase the viscosity and stringiness oi the oil. breaking said viscosity and stringiness by heating at a temperature above 212 F. but below the boiling point or the oil and until the consistency of said oil is reduced to that at which it will flow readily through the lubrication system oif internal combustion engines, and accelerating the viscosity breaking operation by directly contacting the compounded oil with open steam.

14. A process of preparing a liquid lubricant v which comprises dissolving in a mineral lubricating oil a basic metal naphthenate comprising the reaction product of a solution containing a polyvalent metal ion capable of forming oil-soluble basic naphthenates, an aqueous solution of a water-soluble naphthenate, and an alkali hydroxidein an amount sumcient to maintain the alkalinity oi the reaction mixture above pH 7 but below the point atwhich the hydroxide oi said pclyvalent metal is precipitated in substantial quantities, said naphthenate being dissolved in the oil in a quantity suihcient to substantially increase the viscosity thereoi, and breaking the increased viscosity by heating the solution at a temperature above 212 F. but below the boiling point of the oil and until the consistency of said oil is reduced to that at which it will flow readily through the lubrication system of internal combustion engines.

JOHN '1. RUTHERFORD. HENRY A. FRANCIS. 

